Magnesium ions but not ATP inhibit cyclic ADP-ribose-induced calcium release

Richard M Graeff, Rian J. Podein, Robert Aarhus, Hon Cheung Lee

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


The pharmacology of the cyclic ADP-ribose (cADPR)-dependent Ca+2 release mechanism is very similar to that of the ryanodine receptor (RyR). Here we showed that MgCl2, a known inhibitor of RyR, blocked cADPR-induced Ca+2 release in sea urchin egg homogenates with a half maximal concentration of about 2.5 mM. The effect was specific since up to 10 mM Mg+2 had no effect on the Ca+2 release induced by inositol trisphosphate. K2ATP, another known modulator of RyR, at up to 10 mM did not affect the half-maximal concentration of cADPR, which remained at about 96 nM. These results indicate cADPR is a specific Ca+2 release activator and not merely an adenine nucleotide acting on the ATP-site. The inhibitory effects of Mg+2 further demonstrate the similarity between RyR and the cADPR-dependent Ca+2 release system.

Original languageEnglish (US)
Pages (from-to)786-791
Number of pages6
JournalBiochemical and Biophysical Research Communications
Issue number2
StatePublished - Jan 1 1995


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